I know there's a lot to see and do at Epcot Center, but my absolute favourite place in the park is the World Showcase. Where else can you enjoy food, beer, and culture from so many countries for less than a plane ticket to *one* of those destinations?
The China "exhibit" is always cool -- they get kids from the acrobatic team to perform stunts that is always entertaining. Japan has the taiko drums.
Every country has some kind of exhibit to learn more about the history of the country and a lot of them some kind of interactive exhibit like a ride or something. I think all of them also have a kid craft that if your kids do them all they can get a pin or something at guest services. I don't have kids, so I'm not positive, but I see the kids walking around with the crafts.
Every year in the fall they also host the International Food and Wine Festival. This year it's held from October 2, 2006 to November 12, 2006.